1. Technical Field
The subject invention relates generally to static sealing assemblies, and more particularly to those having an elastomeric sealing bead extending upwardly from a first component to create a seal with a second component.
2. Related Art
Various static sealing assemblies are known for creating a fluid-tight seal between mating components. One common type of static seal is a gasket which typically includes a carrier formed of a metal, such as steel, or plastics material on which elongated beads of elastomeric sealing material are adhered. The carrier provides the rigid framework or backbone for properly locating and supporting the sealing beads which, when the components are clamped together, are compressed under pressure to form the fluid-tight seal. Another type of static seal omits the carrier such that the sealing bead is applied directly to the sealing face of one of the two components, but otherwise operates in the same manner to form a seal under compression.
One concern with static seals of either type is that the elastomeric sealing bead not be overcompressed to the point where it ruptures or moves out of position to impair the desired sealing characteristics of the seal. One approach to controlling over deformation of the sealing bead is to mount the sealing bead in a groove of the carrier or sealing face. The groove is shaped and dimensioned relative to the sealing bead to provide a void or air space adjacent to the sealing bead. When deformed under compression, the sealing bead is displaced laterally to fill or partially fill the voids with only a small portion of the sealing bead extending above the groove to provide a fluid-tight seal between the components. Such grooves must have sufficient depth to accommodate the bulk of the sealing bead when in the compressed state. This is particularly problematic with gasket applications since it calls for a fairly thick carrier to accommodate the deep groove for the sealing beads. Not all applications can accommodate such a thick carrier, particularly certain automotive applications where there is a constant trend toward making engines and related components more compact, allowing for less and less space between mating components to achieve a seal. One additional draw back to the deep groove approach for protecting sealing beads on carriers against over-compression is that the deep groove in combination with a thinner carrier reduces the physical strength of the carrier and may impair the sealing characteristics of the seal.
Another approach to controlling over-compression is to build voids or empty spaces into the cross section of the sealing beads, for example providing a void or open channel on either side of a central sealing projection of the bead that runs the length of the bead. Under compression, the central projection is deformed into the voids. One disadvantage to this approach is that the seal material is displaced in opposite directions, putting undue stress on the gasket material which could lead to undesirable fatigue or possibly rupture over time.